I've been using Hubspot for 2 years now and there have been ups and downs.
Their contact management and lead nurturing is amazing for instance. The system makes it very easy to track and optimize your site for conversions.
When we first migrated our site though, the code (html+css+js) was a complete mess and the cms was limiting to say the least.
They've just announced a release of their COS (content optimization system) that will blow away the previous clunky content management. I'm migrating my site over to that in November. It's pricey...The enterprise version that we have is $15000 a year and it only allows for 10,000 contacts at any given time.
If you ever get a chance though, go to their inbound conference next year. I went this year and it was amazing! Look me up if you're planning on going.
